Stair layout square



Dec. 3, 1963 s, BAKER 3,112,568

' STAIR LAYOUT SQUARE Filed May 16, 1960 :9 26 A apnea Home.

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/6 Arraen/EY United States Patent Ofiice 3,112,558 Fatented Dec. 3, 1963 3,112,568 TAIR LAYOUT SQUARE Merton S. Baker, 1128 Somonauir St, Sycamore, Hi. Filed May 16, 196i), Ser. N 29,241 4 Claims. (Cl. 33%} This invention relates to stair layout tools which may be accurately set for laying out the rise and tread simultaneously for any stair rise and number of stairs.

The object of this invention is to improve the efiiciency of the operator by reducing layout time and material waste through miscalculation.

A further object is to provide a layout square with an adjustable straight edge for the hypotenuse of the right triangle having the rise and tread sides or" the square as its legs, and a scale indicating the stair rise for any nu l-- ber of stairs for which the straight edge is automatically set so as to lay out the correct rise and tread on a stringer when the straight edge is placed against the edge of the stringer.

A further object is to provide the above tool with a scale indicating the stair rise for a predetermined nurnber of stairs, and a chart listing calibrations of this scale for other numbers of stairs.

A further object is to provide a central square blade with cam or guide slots and two side pieces on opposite faces of said blade held together by pins guided in said slots, for adjusting a straight edge on said side pieces to ditferent hypotenuse angles with respect to the perpendicular sides of the square blade which represent the desired rise and tread for different stair pitches as represented by the hypotenus angles.

Other and more specific objects will appear in the following detailed description of the invention as illustrated in the accompanying drawings, wherein:

FIG. 1 is a plan view of a stringer showing the application of the square of the present invention for laying out the stairs,

FIG. 2 is an enlarged side view of the layout square,

FIG. 3 is a further enlarged detail sectional view taken on the line 3-3 of FIG. 2, and

FIG. 4 is a diagrarn showing an average pitch line for a stair rise between floors, .for which the square may be designed, giving a shorter run for a greater rise and a longer run for a smaller rise for the same number of stairs.

The stair-square is a precision tool designed to take the mystery out of stair building and increase the efiiciency of the operator by reducing layout time and material waste through miscalculation.

The unit consists of three components. A central square blade and two side pieces 12 and 13 having coplanar straight edges 14 at their base. The two legs 16 and :18 of the central blade 10 form a 90 degree angle. One leg 16 being approximately 12" in length is for the tread and may be calibrated in inches and quarter inches. The other leg 18 being approximately 8 /2 to 8%" long is for the riser and may be calibrated in a like manner. The center blade contains three slots, one straight slot 20, and two arcuate slots 22 and 24. These slots receive pins 26, 2S and 30, which are fixed between the side pieces to guide the blade into position to obtain the correct treadriser combination for each setting made for a known rise and a known number of stairs to be laid out for said rise.

On either side of the blade 1% are two identically shaped side pieces 12 and 13 with five fastening pins. Two of these pins may comprise a bolt and nut fastening 32 to hold the unit together and the other three may be rivets 34, their shanks forming the pins to guide the slots in the blade. At the base of each side piece the edge has a right angle bend forming a straight-edge 14 making the tool reversible during stringer layout. The stair rise calibrations 36 are directly indicated at the riser leg end of the blade, a pointer 38 being formed on the edge of the side pieces 12 for cooperation therewith. When the tool is set for a known rise, the proper tread-riser dimensions and stringer angle are automatically obtained for stringer layout.

The stair rise calibrations on the blade are designated by the rise in inches for a definite number of stairs. A calibration chart 449 is provided in a convenient place on the tool for use in setting the tool properly for several different numbers of stairs. For example, if the average number of stairs used on a building project is twelve for rises ranging between 81" and 96", these rises may be used to designate the calibrations on the tool for use directly, in connection with twelve step stairs, and the chart provided may be as follows:

Base 1 10 R 11 R 12 R 13 R 14 R 67. 5 74. s 81. 0 87. 8 94. 5 68. 3 75. 1 82. 0 88. 8 95. 5 69. 2 76. 1 83. 0 90. 0 90. 9 70. 0 77. 0 84. 0 91. 0 98. 0 70. s 77. 9 s5. 0 92. 0 99. 0 71. 7 78. 8 86. 0 93. 2 100. 3 72. 5 79.8 87. 0 94. 3 101. 5 73. 3 80. 0 88. 0 95. 3 102. 5 74. 2 81. 6 s9. 0 95. 4 103. 8 75. 0 s2. 5 90. 0 97. 5 105. 0 75. 8 s3. 4 91. 0 9s. 5 105.1 75. 7 84. 4 92. 0 99. 7 107. 4 77. 5 s5. 3 s. 0 100. 8 108. 5 7s. 3 86.1 94. 0 101.8 109. 5 79. 2 87.1 95. 0 102. 9 110. 9 s0. 0 s8. 0 90. 0 104. 0 112. 0

1 l3asie readings in middle column (Red) correspond with scale setting on 00 To alter height or number of risers, select Rise column desired and match stair rise being used to Base column for correct setting number.

This chart lists the rises for every inch in the range from 81" to 96 for twelve steps stairs in the middle column, which may be printed or otherwise inscribed in red under the heading 12R. Additional columns of rises may be listed on either side of this column for a lesser number of stairs to the left of the middle column and for a greater number of stairs to the right of this column as shown above, headed by 10R, 11R, 13R and 14R, in accordance with the number of stairs in the corresponding rises listed. The rises listed under each number of stairs are those for which the setting of the tool calibration is found in the same line on the chart in the 12R column, so that the tool may be set accurately for any number of stairs in any stair rise within the range of the chart, with the desired relations between rise and stringer angle in accordance Within the design of the guide pins and slots.

To begin a layout, the operator needs only to measure the total Rise (line AB in FIG. 4) existing on each individual job. With this information, he can set the indicator on the tool to the known Rise calibration or its equivalent for some other number of stairs and this automatically moves the blade to the proper Riser-Tread combination necessary for layout.

He can start at one end of the stringer 42 and scribe around the riser and tread legs as shown by pencil 44 in FIG. 1, according to the number of risers shown on the chart, and his stair layout is complete on one stringer. By reversing the tool, he can lay out the other stringer in the same manner with no change in setting, as indicated in FIG. 3.

From this point on he may either cut, rout, or cleat V 3 the stringer to accept the treads 46 and the risers 48, for the assembly as desired.

By locking the bolt and nut assemblies after tightening the side pieces together sufficiently, enough friction may be provided between the blade and side pieces to hold them in any adjusted position during a layout operation. Alternatively, the assemblies 32 may be loosened with the aid of a screwdriver and pliers for easy adjustment, and then tightened up to hold the parts in fixed adjustment during the layout operation.

Many obvious modifications in the details and design of the guide means to obtain desired relations between rise and stringer angle may be made without departing from the spirit and scope of the present invention, as defined in the appended claims.

What is claimed is:

1. A stair layout tool comprising a square-blade having a tread arm and a rise arm with outer straight edges at right angles to each other,

a side plate slidably mounted over one face of said square blade within the angle of said straight edges, said side plate having a straight edge shoulder extending away from said face within the right angle between the outer straightedges of said arms to define the main portion of the hypotenuse of a right angled triangle completed by said outer straightedges of the square-blade for which the tool is set,

guide means for slidably adjusting said side plate on said blade to control the angle of the hypotenuse in a predetermined relation to the variation of the rise,

a complementary oppositely shouldered side plate slidable on the opposite face of said blade and fixed to said first side plate by a plurality of pins, at least two of which pass through guide slots in said blade to fix said plates together and to provide said guide means, and

at least one other of said pins being located near the oppositely extending shouldered straightedge of said plates,

said other pins comprising a bolt and wing unit assembly for clamping the plates on said blade in adjusted position.

2. A stair layout tool as defined in claim 1, a pointer on a side plate and a scale on the corresponding face of d the blade adjacent thereto and calibrated to indicate the stair rise of a predetermined number of stairs for which the tool is set.

3. A stair layout square comprising a square-blade having arms at right angles to each other and an adjustable plate slidably mounted on one face of said square-blade and having a straightedged shoulder positioned diagonally \between the endportions of said arms to define the main portion of the hypotenuse of a right angled triangle having its perpendicular legs along the outer edges of said arms, said legs representing the rise and tread dimensions of a step for which the square and plate are slidably adjusted, and guide means for adjusting said straightedged shoulder by sliding said plate relatively to said square-blade to vary the rise dimensions of said triangle in a predetermined relation to the angle of said hypotenuse, said guide means comprising pin and guide slot connections between said blade and plate, there being a straight middle slot in said blade substantially radially of the corner of said square-blade, and two arcuate slots near the end portions of said blade, and a complementary plate on the opposite face of said blade and pins fixing said plates together and passing through and guided by said slots to provide a desired locus of positions of said hypotenuse for varying its angle in accordance with the change in the rise dimension of said triangle. 4. A stair square as defined in claim 3, a pointer on one of said plates and a scale on the corresponding face of said blade cooperating therewith, said scale being calibrated to indicate the stair rise of a predetermined number of stairs for which the square is set.

References Cited in the file of this patent UNITED STATES PATENTS 780,954 McCartney -2 Jan. 24, 1905 FOREIGN PATENTS 261,624 Great Britain Nov. 25, 1926 

1. A STAIR LAYOUT TOOL COMPRISING A SQUARE-BLADE HAVING A TREAD ARM AND A RISE ARM WITH OUTER STRAIGHT EDGES AT RIGHT ANGLES TO EACH OTHER, A SIDE PLATE SLIDABLY MOUNTED OVER ONE FACE OF SAID SQUARE BLADE WITHIN THE ANGLE OF SAID STRAIGHT EDGES, SAID SIDE PLATE HAVING A STRAIGHT EDGE SHOULDER EXTENDING AWAY FROM SAID FACE WITHIN THE RIGHT ANGLE BETWEEN THE OUTER STRAIGHTEDGES OF SAID ARMS TO DEFINE THE MAIN PORTION OF THE HYPOTENUSE OF A RIGHT ANGLED TRIANGLE COMPLETED BY SAID OUTER STRAIGHTEDGES OF THE SQUARE-BLADE FOR WHICH THE TOOL IS SET, GUIDE MEANS FOR SLIDABLY ADJUSTING SAID SIDE PLATE ON SAID BLADE TO CONTROL THE ANGLE OF THE HYPOTENUSE IN A PREDETERMINED RELATION TO THE VARIATION OF THE RISE, 